In 1983 Winfrey moved to Chicago to host a low-rated half-hour morning talkshow, AM Chicago. Within months of her taking over, the show overtook Donahue as the highest-rated talkshow in Chicago. It was renamed The Oprah Winfrey Show, expanded to a full hour, and broadcast nationally from 8 September, 1986

(Foreground, from left) Akosua Busia, Winfrey, Whoopi Goldberg and Rae Dawn Chong in the 1985 film The Colour Purple. This was the first venture for Oprah's production company, Harpo – Oprah spelt backwards

Winfrey in November 1996 talking to author Toni Morrison, whose novel Song of Solomon was back in the spotlight 19 years after its initial publication following the talkshow host's decision to select it for her book club. Winfrey's endorsement has long been regarded as a surefire way to guarantee a place in bestseller lists

The 1998 film Beloved, which starred Winfrey, Thandie Newton and Kimberly Elise. Despite dedicating two episodes of her hit talkshow to her film, it opened to poor box-office results and ended up losing her millions of dollars

Winfrey on the cover of the September 2001 issue of O. The publisher of a German erotic title, O Magazine, filed a lawsuit in federal court in August 2001 in New York claiming Winfrey's title was guilty of trademark infringement and unfair competition

Tom Cruise jumps on the sofa during The Oprah Winfrey Show on 23 May 2005, proclaiming his love for his then new girlfriend Katie Holmes, prompting raised eyebrows worldwide. The talkshow has always been famed for its self-help culture and ability to get celebrities to open up

Winfrey and Halle Berry at the Roosevelt Hotel in Hollywood in 2005, celebrating the premiere of Their Eyes Were Watching God. Berry starred in the made-for-TV movie, which was produced by Winfrey's production company Harpo

Winfrey in January 2007 opening the multi-million dollar school she funded for poor South African girls in Johannesburg. The academy was the culmination of a pledge she had made six years previously to the anti-apartheid icon Nelson Mandela, who also attended the opening

Winfrey listens as Democratic presidential hopeful Barack Obama addresses a crowd at a campaign rally on December 8, 2007 in Des Moines, Iowa. Oprah supported Obama all the way through his campaign and by some estimates gained him one million votes election day